Early in the process for son, when the target list was very wide, he did get some responses and follow-up dialog but it was not a high percent by any stretch and it was, as one may expect, far more likely for it to be from schools that probably struggled to get decent prospects.
There are no magic pills. The more you can connect with a school with the right skill set, the right grades, the right connections/coaches/travel orgs/mentors speaking on your behalf, getting in the right places to be seen by targeted schools, fitting the right need at the time, etc., the better the chances.
There are exceptions - moreso with HA's, D3's, etc., but again, it makes sense. Those schools are more motivated to coax anyone who can qualify academically and financially to attend.
Additionally, if the skill set and player track record gives good indication that the player can excel at a given school, they will be more likely to respond. But those players will usually use more effective methods of communicating to such schools than just an unsolicited email.